I 



40 CONTRIBUTION TO THE PALEONTOLOGY OF TRINIDAD. 



by d'Orbigny and others by Charles wort h , I am satisfied that they are distinct. 

 The beak is so small as to be almost obsolete, and there is always a more or less 

 distinct, rounded, umbonal ridge. In general form, it resembles G. (Exogyra) 

 columba, but wants the spiral beak, and is never lobed. The small beaks and 

 absence of all traces of lobes will sufficiently separate it from G. pitcherii. 



"Length 1.7 in. Greatest width 1.3 in." 



Type locality, Nanafalia, Alabama, in the Lignitic Eocene. 



Remarks. — This is a very common shell in the fauna of Bed No. 6, Soldado 

 Rock. Specimens from that locality match exactly in size and shape others from 

 Nanafalia, Alabama. The species has been found only in the Lignitic. 



Geological horizon. — Lignitic Eocene. 





Ostrea abrupta d'Orb. variety ? Plate V, Figures 1, 2. 



Cf. Ostrea abrupta d'Orbigny, Voyage dans l'Amenque Mend., T. 3, 4 e partie (Pal6ontologie), 

 p. 93, pi. 21, figs. 4-6. Republished by Coquand, Monog. du Genre Ostrea, Terrain Cr6tace\ 

 p. 175, pi. 63, figs. 1-3. 



Mr. Veatch found in Cretaceous beds on the route to El Pilar, near Coycuar, 



Venezuela, a slab with plicated oysters which Dr. Stanton refers to the group of 



Ostrea abrupta, described by d'Orbigny from the Cretaceous of Colombia. Dr. 



Stanton adds, however, that the Venezuelan specimens are much smaller than 



the type and lack some other characteristics. So that in order to identify them 



with d'Orbigny's species it would be necessary to assume that the specimens are 



immature and that the species varies even more than the original description 

 indicates. 



Geological horizon. — Cretaceous. 



Ostrea puelchana d'Orb. Plate V, Figures 3-5, 9, 10. 



On the Union Estate, Brighton, Trinidad, Mr. Veatch found two horizons 

 characterized by oyster shells. These at first seemed to be distinct species, but 

 the difference is chiefly one of size. They are referred by Dr. Dall to 0. puel- 

 chana, which Dr. Dall suggests might be shown to be a southern form of virginica 

 if a complete series could be obtained . 



It is interesting to note also that Dr. Guppy has referred the specimens of 

 O. fmiterms Sby. found on Trinidad to virginica. The probabilities are that this 

 was the very species that Dr. Guppy had in mind. For certainly the Union 

 Estate shells are remarkably close to a varietal form of virginica now living in 

 the Gulf of Mexico. y 



Localities.-The large form was found in a bed 1000 feet north of the Forest 

 Keserve Road. This bed is stratigraphically about 4000 feet above the Soldado 



StJ!^ a layer half a mil e from Bamboo Junction. 



!2 f th,S ^ hGS 21 ° feet below the law oyster horizon. 

 Geological horizon.- -Upper Oligocene. 



bed 



